RT Journal Article SR Electronic T1 High body mass index is associated with increased risk for osteoarthritis of the first carpometacarpal joint during more than 30 years of follow-up JF RMD Open JO RMD Open FD EULAR SP e001368 DO 10.1136/rmdopen-2020-001368 VO 6 IS 3 A1 Mattias Rydberg A1 Lars B Dahlin A1 Anders Gottsäter A1 Peter M Nilsson A1 Olle Melander A1 Malin Zimmerman YR 2020 UL http://rmdopen.bmj.com/content/6/3/e001368.abstract AB Introduction Osteoarthritis (OA) of the first carpometacarpal (CMC-1) joint is a common hand disorder with symptoms including pain and weakness of the thumb. Previous studies have associated high BMI with OA of weight-bearing joints, whereas studies regarding non-weight-bearing joints have shown conflicting results. Thus, the aim of this study was to investigate the influence of overweight and obesity on incident OA of the CMC-1 joint.Method During 1974 to 1992, 33 346 participants aged 26–61 years were included in the population-based cohort Malmö Preventive Project. Endpoint data were retrieved from Swedish national registers until end of 2018. Sex-stratified Cox regression models adjusted for potential confounders were calculated using BMI as a continuous variable and stratified for normal weight, overweight and obesity.Results Median follow-up was 36 years for men and 32 years for women. A one-unit increment of BMI was independently associated with incident OA of the CMC-1 joint in men (HR 1.12; 95% CI 1.09 to 1.15, p<0.001) and women (HR 1.05; 95% CI 1.03 to 1.08, p<0.001). Stratifying for BMI groups, obesity was independently associated with OA of the CMC-1 joint in men (HR 3.57; 95% CI 2.68 to 4.77, p<0.001) and women (HR 1.98; 95% CI 1.44 to 2.73, p<0.001).Conclusion High BMI and obesity are major risk factors for OA of the CMC-1 joint. The association was stronger among men but could be demonstrated also among women. Future studies are warranted to clarify underlying pathophysiological mechanisms for this association, enabling identification of potential therapeutic targets related to obesity in order to prevent the development of OA of the CMC-1 joint.